A Qualitative Assessment of Sponge-Feeding Organisms from the Mexican Pacific Coast

ABSTRACT

Predation is one of the most important structuring mechanisms of benthic communities. The objectives of this study were to identify the main predators of sponges, and their principal prey, in two localities from the Sea of Cortez (Mexican Pacific Ocean). For this, 60 stomach contents were analyzed from 13 species of fishes, 23 species of opisthobranchs, and 4 species of echinoderms (urchins and starfishes). Two species of fish (Pomacanthus zonipectus and Holacanthus passer), and five species of opisthobranchs (Hypselodoris agassizii, Glossodoris sedna, Glossodoris dalli, Discodoris ketos and Tylodina fungina) included sponges in their diet. Sponge remains were not found in the echinoderm stomach contents. The two species of fish fed on 26 species of sponge; the most common were Haliclona caerulea and Spirastrella decumbens. The opistobranchs fed on 19 species, mostly Haliclona caerulea and Tethya taboga. In Mazatlán Bay there are 70 sponge species reported, and fishes and opisthobranchs feed on 46% of the species present, but predation seems to have little effect on distribution and abundance of sponges in this locality.